This invention relates to disilane compounds and to a method for their preparation. More particularly, this invention relates to hexakis(monohydrocarbylamino)disilanes and to a method for the preparation thereof.
Silane compounds such as monosilanes and disilanes are used in a variety of applications. In the field of semiconductors, silane compounds are frequently used as starting materials for the production by chemical vapor deposition (CVD) of silicon-based dielectric films of, e.g., silicon nitride, silicon oxide, or silicon oxynitride. More specifically, silane compounds can produce silicon nitride by reaction with a nitrogen-containing reaction gas such as ammonia, silicon oxide by reaction with an oxygen-containing gas such as oxygen, and silicon oxynitride by reaction with a nitrogen-containing gas and an oxygen-containing gas.
At present the standard method for producing silicon nitride films by CVD involves inducing a reaction between ammonia gas and dichlorosilane (=the silane compound); however, ammonium chloride is produced as a by-product by this reaction. Ammonium chloride is a white solid and as such accumulates in and clogs the—exhaust lines of the CVD reaction apparatus. A CVD method is therefore required in which the starting material is a chlorine-free silane compound. It is also desirable during the production of silicon nitride, etc., by CVD technology to obtain good film—deposition rates at low temperatures (at or below 600° C.).
Tetrakis(dimethylamino)silane and tetrakis(diethylamino)silane have been examined as chlorine-free silane compounds, but these aminosilane compounds suffer from the problem of providing slow film—deposition rates at low temperatures.
The chlorine-free alkylaminodisilanes are also known. These alkylaminodisilanes are solids at ambient temperatures. For example, —hexakis(dimethylamino)disilane is reported to undergo sublimation at 230° C. under reduced pressure. Compounds that are solids at ambient temperature have poor handling characteristics.
An object of this invention, therefore, is to provide novel silane compounds that are free of chlorine, that provide excellent film—depositing characteristics at low temperatures in the case of silicon nitride films, etc., and that also have excellent handling characteristics. An additional object of this invention is to provide a method for preparing these novel silane compounds.